1) Field of the Invention
The field of this invention relates to impoundments and specifically to the removal of accumulated water from an impoundment.
2) Description of the Prior Art
The subject matter of the present invention will be discussed primarily in conjunction with a landfill. However it is considered to be within the scope of this invention that this invention could be utilized with other impoundments. As far as this invention is concerned, an impoundment is to include any material that is contained within an enclosure. Typical material could comprise a liquid, such as a brackish water, and also it can comprise leachate from a solid waste landfill. The enclosure frequently will be formed within a recess formed within soil. However, the enclosure could also be a non-soil enclosure such as a fabricated type of structure.
Within the United States, the incineration of solid waste is restricted due to the potential for creation of air pollution. Therefore, communities have selected the use of a landfill for disposal of solid waste. A landfill generally takes the form of a ravine so that the natural configuration of the terrain can be utilized to form a large container into which the solid waste is deposited. The bottom or floor of this ravine is covered with a thick plastic sheet. Liquids from within the solid waste will settle to the bottom and rainwater will also be passed through the solid waste to the bottom. The liquid that accumulates at the bottom is called leachate. Mounted within the landfill at the bottom is a leachate removing pipe. A typical leachate removing pipe is a length of pipe, generally a plastic pipe, that is basically porous as by including a mass of holes through its sidewall along its longitudinal length. The leachate is to be moved by a pump through the leachate pipe exteriorly of the landfill and deposited at an exterior location. This leachate is considered to be a waste material, and generally it requires the leachate to be transported to a liquid waste treatment and disposal facility that is designed for the disposal of hazardous liquid waste material. This may require the transporting of the leachate hundreds of miles and the application of expensive treatment procedures. Inherently, the treatment and disposal of leachate is an expensive procedure.
Although the leachate may contain numerous dissolved and suspended solids, the primary constituent in leachate is water. Water not only is released from the solid waste but also the landfill receives water from rain. The landfill and the surface impoundment in which leachate is frequently stored is subjected to evaporation due to heat from the sun. However, in wet climates, the annual precipitation will be greater than the amount of evaporation. Therefore, if something can be done to increase the evaporation rate within the surface impoundment, then a substantially lesser amount of leachate can result with this leachate being far more concentrated containing dissolved and suspended solid materials requiring the treatment and disposal of a substantially smaller volume of this leachate. If all of the water can be removed from the leachate, it may be suitable for disposal without additional treatment in the same landfill from where it was generated.